Protein quality and amino acid profiles of fish products available in Poland

Chemical analyses were carried out on 18 of the most popular varieties of fish products in the Polish market (canned, smoked, salted and marinated fish of different species), produced by the largest manufacturers and distributors in the country. The contents of the nutritive substances in the fish products (proteins, amino acids, and fats) were determined. To assess the nutritional quality of proteins in these products, the protein digestibility was determined, which ranged from 77.0% to 98.7%, and the amino acid composition of each of these groups of products was compared with that of a standard protein recommended by the World Health Organization (WHO). In addition, protein digestibility-corrected amino acid scores (PDCAAS) were calculated. Relative to the WHO protein standard, most of the fish products tested scored very high, with values ranging between 0.9 and 1.0. This study confirmed that in terms of both quantity and quality, fish products in the Polish market could serve as a significant source of essential amino acids and that the sulphur-containing essential amino acids and lysine present in fish products could supplement the corresponding deficiency in plant proteins. However, it was also indicated that drastic thermal processes, such as sterilisation, could influence the protein digestibility.